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71 terms

Muscular System

Complete Study Guide
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The capacity of a muscle cell to shorten forcefully is known as
contractility
Muscles exhibit the property of excitablity. This means the muscle
responds to stimulation by the nervous system.
Identify the statement concerning general functional characteristics of muscle that is true.
Muscle tissue shortens forcefully but lenghtens passively.
Which of the following actions is caused by contraction of skeletal muscle?
moving your feet and walking.
True or False? Smooth muscle is found in the walls of hollow organs?
True
Skeletal muscle fibers
possess striations
A faciculus
is surronded by perimysium
Fascia
surrounds individual muscles.
Muscle myofibrils
contain myosin and actin myofilaments.
Which of the following is composed of myosin molecules?
thick myofilaments
The active sites to which cross-bridges attach are found on the
myosin myofilaments
ATPase is found in
myosin heads.
T tubules are invaginations of the
sarcolemma
The sarcoplasmic reticulum
stores calcium ions.
True or False? Both actin and myosin myofilaments shorten during contraction.
False
The sites where a chemical substance is transmitted from the presynaptic terminal of an axon to the postsynaptic membrane of a muscle fiber are called
neuromuscular junctions.
Electrical signals called action potentials
causes muscles to contract
The outside of the resting plasma membrane is _____ relative to the inside of the resting plasma membrane.
positively charged
Which of the following situations occurs in electrically excitable cells?
Depolarization causes voltage-gated sodium ion channels to open.
Depolarization of the cell membrane occurs when there is a rapid influx (inflow) of
sodium ions.
An action potential
occurs when the local potential reaches threshold level.
A stimulus either causes an action potential or it doesn't. This is called
an all-or-none response.
When repolarization of the cell membrane is complete, the
cell no longer has a potential difference across its membrane.
Synaptic vesicles in the neuromuscular junction contain
acetylcholine
What contains postsynaptic membrane, presynaptic terminal, synaptic cleft and receptors on postsynpatic membrane?
neuromuscular junction
Acetylcholine binds to a membrane bound receptor and causes ligand-gated sodium channels to open and results in
depolarization
When action potential reaches the presynaptic terminal,
calcium ions diffuse into the presynaptic terminal through voltage-gated ion channels.
Lack of acetycholinestrase in the synaptic cleft would result in
continuous stimulation of the postsynaptic membrane.
Too much acetylcholinesterase causes
rapid degradation of acetycholine.
Curare blocks acetylcholine receptors at the motor end plate. This would result in
inability of the muscle fiber to respond to nervous stimulation.
A child ingested organophosphate poison used to kill insects. Soon the child's muscles began tetanic contractions. Predict what occured the synpatic cleft.
increased accumulation of acetylcholine in the synapse.
One cause of spatic paralysis might be
inhibition of acetylcholinesterase
The model that describes the contraction of the muscle is called the
sliding filament model
If sodium ions cannot enter a muscle fiber in response to a stimulus,
contractions cannot occur.
During the contraction phase of a muscle twitch,
actin-myosin cross-bridges form.
A muscle fiber will respond to a stimulus when that stimulus reaches the ____level.
Threshold.
True or False? A threshold stimulus will cause contraction of a muscle fiber?
True
Which of the following would occur as a result of a single muscle contraction?
Twitch
A sustained muscle contraction is know as
tetanus
Tetanus of a muscle is though to be caused by
high calcium ion concentrations in the sarcoplasm.
A condition in which stimuli occur so rapidly that there are no intervening relaxations between contractions is called
complete tetanus
Treppe
can contribute to improve muscle efficiency, may be due to an increase in the level of calcium ions around the myofibril, is an example of a graded response, is acheived during warm-up exercises.
Which of the following would contribute to muscular fatigue in the muscle fiber?
depletion of ATP reserves
The type of muscle fatigue known as " psychological fatigue" is the result of
the emotional state of an individual
Rigor mortis occurs after death because
cross-bridges form but can't release
During resting conditions, _______ is synthesized to store energy?
creatine phosphate
A waste product of anaerobic respiration in muscle cells is
latic acid.
Which of the following occurs during recovery from oxygen debt?
conversion of excess latic acid to glucose
Oxygen debt represents
the amount of oxygen that cells need to replenish ATP supplies after exercise
describe myoglobin's special function in muscle tissue?
it acts as a reservoir for oxygen
Body temperature
results from the heat procduced when muscles contract.
The sternocleidomastoid muscle extends from the mastoid process of the temporal bone to the sternum and medial clavical. When both sternocleidomastoid muscles contract, the head is flexed. The end of the muscle that connects to the sternum is the
insertion
What muscle is known for its shape?
trapezius
Which of the following muscles is named for its location?
quadriceps femoris
Raising the eyebrows is the action of the _____ muscles.
occipitofrontalis
Closing or puckering the lips is the action of the______ muscle.
obicularis oris
Which of the following muscles is involved in chewing gum?
masseter
The major movement produced during quiet breathing is accomplished by the
diaphragm
If abdominal muscles are contracted while the vertebral column is fixed this will aid in
vomiting, childbirth, urination and defecation.
Which of the following muscles of the chest has its insertion on the humerus?
pectoralis major
Which of the following muscles moves the scapula?
trapezius
The infraspinatus
adducts and laterally rotates the arm.
Raising your arm to shoulder level is accomplished almost entirely by the
deltoid
The teres major and teres minor are not involved in
adduction of the arm
Which of the following muscles extends the forearm and has its insertion on the ulna?
triceps brachii
Which of the following is part of the quadriceps femoris muscle group?
vastus lateralis
Which of the following muscles would be considered and antagonist to the rectus femoris?
biceps femoris
Of the following muscles of the leg, which one is on the anterior side of the leg?
tibialis anterior
of the following muscles of the thigh, which one is on the posterior side?
biceps femoris
Of the following muscles of the thigh, which one does NOT pull the leg foward?
biceps femoris
The term ''shin splints" is applied to
stress fractures of the fibula 2 to 5 cm distal to the knee.